The second nerve agent emergency in four months prompted a diplomatic row, with Home Secretary Sajid Javid accusing the Russian state of using Britain as a "dumping ground for poison". It said Moscow had proposed a joint investigation but that the proposal remained without response. "We urge British law enforcement not to get involved in dirty political games", foreign ministry spokeswoman Maria Zakharova told reporters.
Zakharova told reporters Thursday that "this government and specifically its leadership will one day have to apologise to Russian Federation and the global community".
The couple, whose identities have not been released but whom the Associated Press has identified as Dawn Sturgess and Charlie Rowley, is in critical condition at Salisbury District Hospital.
The 44-year-old died on Sunday evening at Salisbury District hospital, Scotland Yard has confirmed.
Michelle Jordan, a local resident in Amesbury, says she's had to tell her two children not to touch anything when they go to the park and to wash their hands. United Kingdom authorities quickly attributed their condition to exposure to "Novichok" - the substance the United Kingdom claims was used to poison Sergei Skripal and his daughter in March this year.
England's chief medical officer Sally Davies said the public should "be careful of picking up any unknown or already risky objects such as needles and syringes".
A police officer also underwent a precautionary test at a hospital to check for possible contamination related to the case, but Wiltshire Police said late Saturday that he had been cleared.
"We would like to reiterate the advice from Public Health England that the risk to the wider public remains low", the hospital said.
Police do not believe Rowley and Sturgess were the victims of a targeted attack, but rather came into contact with remnants of the poison somewhere in Amesbury or Salisbury. "Novichok's designed by the Russians to overmatch North Atlantic Treaty Organisation chemical defence capabilities, we can not detect it". It's walking distance from where the Skripals collapsed last March.
Kremlin spokesman Dmitry Peskov also said that Moscow had offered Britain its assistance in probing the Salisbury attack long ago but had been rebuffed.
'The MP (John Glen) made the point of coming to speak to us and said these visits are managed for him. "It's like he was in another world, hallucinating". The new victims are both critically ill in the same hospital that treated the Skripals. In a televised statement in the House of Commons, he added that the latest couple is thought to have been exposed to the nerve agent at a location not previously associated with the Skripals incident.